Security gates are known for this purpose comprising elongated rods which extend across the opening either horizontally or vertically with pivoted connections that extend between the rods at right angles thereto. Typical of such gates are those shown in U.S. Pat. No. 2,940,520 (Cookson et al), U.S. Pat. No. 3,231,005 (Cookson et al), U.S. Pat. No. 3,490,514 (Duncan et al), U.S. Pat. No. 3,601,175 (Wardlaw), FR 1.183.386 (Coulon) and GB 581,560 (Griggs et al). While having a number of advantages, these gates have the disadvantage that the gate has to be rolled on to a roller for storage and the roller takes up a considerable amount of space. U.S. Pat. No. 1,654,857 (Brady) and U.S. Pat. No. 1,864,796 (Brady) also show arrangements in which the rods are moved into storage spaces that have to be allowed for them.
It is also known to make such gates with inclined connections which slide relative to one or more of the rods into a position very nearly parallel to the rods when the gate is in the open position and to an inclined position when the gate is in the protective position spanning the opening. Examples of such a gate are shown in U.S. Pat. No. 1,290,176 (Griffith) and U.S. Pat. No. 4,006,768 (Horgan). Although these gates are usually very easy to use, they are usually made of fairly light material and the connections normally would present no undue problem to the professional thief who wishes to cut through them. In addition when all the connections between two adjacent rods are cut, the gate can be opened easily by pushing the gate parts towards the ends of the gate which are secured to e.g. the walls of the opening. In this context the connections will always be exposed when the gate is in the protecting or open position and will not be protected by any robust plates which may inhibit a thief.
More robust gates have been made with some of the rods being guided so that the gate collapses. U.S. Pat. No. 641,262 (Bode), U.S. Pat. No. 1,945,729 (Callender), U.S. Pat. No. 2,493,815 (Guilberti) and GB 722,961 (Hill) illustrate typical examples of such gates. These gates normally have vertical rods which are connected together by horizontal connecting pieces. The ends of alternate rods (hereinafter called "the guided rods") are guided in horizontal guide-ways that run above and below the opening. Thus when it is desired to move the gate into the open position, the guided rods are moved towards each other and the rods between them are moved outwardly so that the gate takes up a compact position. In order to make the rods and connecting pieces sufficiently strong to resist being cut by, say, a hack saw, these parts have to be made of heavy metal. This tends to make the gate extremely heavy and difficult to move from the protective to the open positions.